Process for treating a hydrocarbon-containing feed

Abstract

A process for treating a hydrocarbon-containing feedstock is provided in which a hydrocarbon-containing feedstock comprising at least 20 wt. % of heavy hydrocarbons is mixed with hydrogen, hydrogen sulfide and a metal-containing catalyst at a temperature of 375° C. to 500° C. and a pressure of from 6.9 MPa to 27.5 MPa to produce a vapor comprising a first hydrocarbon-containing product, where the hydrogen sulfide is mixed with the feedstock, metal-containing catalyst, and hydrogen at a mole ratio of hydrogen sulfide to hydrogen of at least 1:10. The vapor comprising the first hydrocarbon-containing product is separated from the mixture, and, apart from the mixture, the first hydrocarbon-containing product is contacted with hydrogen and a catalyst containing a Column 6 metal at a temperature of 260° C.-425° C. and a pressure of from 3.4 MPa to 27.5 MPa to produce a second hydrocarbon-containing product.

Description

PRIORITY CLAIM[0001]The present application claims the benefit to priority of U.S. Provisional Application No. 61 / 421,844 entitled “Process for Treating a Hydrocarbon-Containing Feed” filed Dec. 10, 2010.FIELD OF THE INVENTION[0002]The present invention is directed to a process for treating a hydrocarbon-containing feedstock.BACKGROUND OF THE INVENTION[0003]Increasingly, resources such as heavy crude oils, bitumen, tar sands, shale oils, and hydrocarbons derived from liquefying coal are being utilized as hydrocarbon sources due to decreasing availability of easily accessed light sweet crude oil reservoirs. These resources are disadvantaged relative to light sweet crude oils, containing significant amounts of heavy hydrocarbon fractions such as residue and asphaltenes, and often containing significant amounts of sulfur, nitrogen, metals, poly-aromatic hydrocarbon compounds, and / or naphthenic acids. The disadvantaged crudes typically require a considerable amount of upgrading, for exa...

AI Technical Summary

Problems solved by technology

These resources are disadvantaged relative to light sweet crude oils, containing significant amounts of heavy hydrocarbon fractions such as residue and asphaltenes, and often containing significant amounts of sulfur, nitrogen, metals, poly-aromatic hydrocarbon compounds, and / or naphthenic acids.

The disadvantaged crudes typically require a considerable amount of upgrading, for example by cracking and by hydrotreating, in order to obtain more valuable hydrocarbon products.

Typically, the separated fractions may be hydrotreated to reduce sulfur, nitrogen, and metals content of the fractions since heteroatoms and metals are undesirable in hydrocarbon products produced from the light distillate fractions, and act as hydrocracking catalyst poisons in the vacuum gas oil fraction and residue fraction.

Furthermore, in a conventional process a large percentage of the sulfur and nitrogen are concentrated in high molecular weight heteroatomic hydrocarbons so that the sulfur and nitrogen become refractory, rendering removal of most or all of the sulfur or nitrogen from the hydrocarbon product difficult.

Current “whole crude” heavy oil or bitumen feedstock upgrading processes also suffer from the production of excess coke and gas, and typically a maximum of about 70%-75% of the carbon content of the disadvantaged crude feed material is captured as non-residue, non-asphaltenic hydrocarbons that are liquid at STP.

Current “whole crude” heavy oil or bitumen feedstock upgrading processes also create substantial quantities of refractory sulfur and nitrogen heteroatomic hydrocarbon compounds thereby rendering removal of most or all of the sulfur or nitrogen from the product difficult.

Formation of coke, refractory sulfur compounds, and refractory nitrogen compounds is a particular problem in upgrading and refining heavy crudes and bitumen, whether as “whole crude” feedstocks or as fractions of a heavy crude or bitumen, that has limited the yield of desirable liquid hydrocarbons from such feedstocks.

The second reaction is undesired and leads to the production of coke and refractory sulfur and nitrogen containing heteroatomic hydrocarbons.

Hydrocarbon-containing feedstocks having a relatively high concentration of heavy hydrocarbon molecules therein are particularly susceptible to coking due to the presence of a large quantity of high molecular weight hydrocarbons in the feedstock with which cracked hydrocarbon radicals may combine to form proto-coke or coke.

As a result, yields of non-residue, non-asphaltenic hydrocarbons that are liquid at STP from heavy crude oils and bitumen have been limited by coke formation induced by the cracking reaction itself.

These molecules are also particularly susceptible to annealation due to the large quantity of large, high molecular weight sulfur- and nitrogen-containing heteroatomic hydrocarbons in heavy oil and bitumen feedstocks.

As a result, large quantities of refractory sulfur- and nitrogen-containing heteroatomic hydrocarbons are formed in conventional cracking processes when utilizing a heavy crude oil or bitumen as a feedstock.

A desirable characteristic of coking is that it tends to concentrate large aromatic ring structures, sulfur, nitrogen, and metals in the coke—leaving cracked, lighter hydrocarbon fragments of improved quality relative to the residue fraction of the feedstock—but this concentration effect is obtained at considerable expense in liquid product yield.

Numerous catalysts have been developed for use in processes for hydroprocessing disadvantaged hydrocarbon feedstocks, either as “whole crude” feeds or as heavy fractions of a heavy crude oil or bitumen, however, such catalysts have not eliminated problems associated with coking and production of refractory sulfur and nitrogen compounds, and catalyst activity may be significantly reduced over time by accumulation of coke on the catalyst.

The formation of coke or sediment may be controlled by limiting the degree of conversion of residue range hydrocarbon in the feedstock to lighter hydrocarbons, which results in a yield loss with respect to the lighter, higher valued, hydrocarbon fractions.

If not controlled, the formation of insoluble coke or sediment may lead to detrimental fouling of the residue hydroprocessing equipment and catalysts.

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